Electric heater for softening thermoplastics



June'7, 1949. J. v. CALHOUN ELECTRIC HEATER FOR SOFTENING THERMOPLASTICSa Sheets-Sheet 1 Filed July 8, 1947 IINF I H H I I I \l l l f l f nhnJMH h H u 5 B 5 Wm H 5 2 my O 1 9. 4 I, 2 M I: 7 I a 3 ||l| JUHN v.EALHUL/N IN VEN TOR.

ATTORNEY June 7, 1949. J. v. CALHOUN ELECTRIC HEATER FOR SOFTENINGTHERMOPLASTICS Filed July 8, 1947 3 Sheets-Sheet 2 JUHN v. EALHUL/NINVENTOR.

ATTORNEY J. v. CALHOUN ELECTRIC HEATER FOR SOFTENING THERMOPLASTICS June7, 1949.

3 Shets-Sheet 3 7 Filed July 8, 1947 JUHN v. L'ALHUL/N INVENTOR.

.iIL rxllllL ATTORNEY Patented June 7, 1949 UNITED-;; Es PAT E'NT or F1c E;

ELECTRIU=HEA-TER FORSOFTENING THEBMOPLASTICS John. V. CalhoumrHaverford,2a., assignor to Edwin Ii. Wie'gand'Company, Pittsburgh, Pa., acorporation ofPelinsylvania Applicatiomlulyfi; 1947,; SeriaIsN o. '759,557

2 Claims? (Cl-i 219-19) Myinvention relatesgto electric, heating and.

a principal object of my .inventiomislthe, provi. sion of an electricheater satisfactory for melting or softening viscous or other materialin a container, thus to facilitate-removal ofthe material from thecontainer.

In this application I have shown- :and- 'described, for purpose ofillustration; oneembodiment which'my invention'may assume, and in thedrawings accompanying this specification and. forming part of thisapplicationz Figure I isa'view of an electricheater.according, to myinvention, partiallydnfront elevation andpartially in vertical section;I.

Figure 2 is. a top planviewofthe heatermf Figureil; I

Figures 3, 4, and 5','are transverse sectionsron the lines 33, 4'-'4,and 5-5; of Figure I'; and

Figure 6 is a circuit diagram showing one manner in which the heater maybe connected.

The electric heater herein shown and described comprises two sheathedembedded-resistor electric heating elements II, herein shown astriangular in cross-section, having their active sections I2 disposed inrecesses in the lower face of a base I3, having their terminal portionsI4 rising through openings I5 provided in the base I3, and held inposition by means of a face plate I6 overlying the lower face of thebase I3 and herein shown as secured to the base I3 by means of a seriesof bolts II extending through alined apertures in the face plate I6 andbase I3.

Rising from the base I3 is a frame herein shown as comprising two tubesI8 screw-threaded in the openings I5 in the base I3, Ts I9 screwthreadedto the upper ends of the tubes I8, nipples 20 screw-threaded into theside openings of the Ts I9, and a union 2I connecting the two nipples 20and completing a cross-brace between the two sides of the frame, whilewelded or otherwise suitably secured to the upper ends of the Ts I9 is asheet metal housing 22 containing a thermostatic switch 23 adjustable bymeans of a knob 24 positioned above the top of the casing 22.

With this construction the electric heating elements II are energizedunder control of the thermostatic switch 23 by means of conductors 25extending from the heating element terminals 26 through the tubes I8 andTs I9 into the interior of the casing 22 and connected to thethermostatic switch 23, and conductors 21 extending to the thermostaticswitch 23 from a suitable source of electric power, and the thermostaticswitch 23 is responsive to operating temperature by means of athermostat bulb 2.8. car-1 ried by a cross-frame 36 clampedrto the-tubesI3 a'ndoperatively connected to the thermostatic switch-2 3. by means ofa connecting tube indicated at 29.

To produce balanced heating of the faceplate I6, preferably the twoelements II are. at-least approximately equal, and to avoid inductanceon alternating current,preferably the conductors 2 1 are so. connectedto. the thermostaticswitch 2.3; that. the two currentswithinreach. oftheitubes I8 andTs i9 flow in opposite.direction for example, asindicated by the diagram-,Figureaii;--

In operation,.the heater is placed in position with the faceplateAfi.restingontheviscous-or other. material to be heated orsoftened; the thermostatic switch isset forlthedesiredvteme perature,and thereupon the heater will progressively melt or soften the viscousor other material, whereby the material may be removed from thecontainer, but avoiding any temperature that would injure the material,and particularly important in this respect is the location of thethermostat bulb 28 substantially above the base I3, whereby theoperation of the device is responsive directly to the temperature of thesoftened or melted material.

After operation any material that may have entered the tubes I9 may flowout through openings 29, while for convenience in handling preferablythe heater is provided with handle means herein shown as comprising aplate 3| embracing the tubes 58 immediately below the Ts I9, a lowerchannel 32 extending transversely below the plate 3!, an upper channel33 extending transversely above the top of the housing 22, connectingbolts 34 extending between the lower channel 32 and the upper channel33, and an eye-bolt 35 secured to the upper channel 33.

As will be understood, the heater is made relatively heavy, whereby theapparatus will come into close contact with the viscous or othermaterial and further will descend into the material as rapidly as themelting or softening is accomplished, and to facilitate the latterfunction preferably the base I3 and face plate I6 are provided with aplurality of apertures 31, as shown.

From the foregoing it will be apparent that the embodiment of myinvention herein shown and described accomplishes the objectspecifically stated. Further it will be apparent that the saidembodiment also accomplishes various other desirable objects andembodies various desirable advantages. On the other hand, obviouslyvarious changes and modifications may be made, and

various other embodiments may be substituted, within the spirit of myinvention, and retaining some or all of the advantages andaccomplishments of the present embodiment, and accordingly it will beunderstood that the present disclosure is illustrative only, and that myinvention is not limited thereto.

Whereupon I claim:

1. An electric heater particularly for melting or softening a body ofmaterial within a .container to facilitate removal of the material fromthe container, comprising a platen adapted to be imposed on the body ofmaterial, metalsheathed electric heating means carried by said platenconstructed and arranged to heat said platen to cause said platen toimpart heat to said material to melt or soften said material, structuralmeans comprising a superstructure disposed a substantial distance abovesaid platen and duct means rising from said platen and connecting saidplaten and said superstructure, electric conductors for supplyingelectric energy to said heating means, connected to said heating meansand extending through said duct means, and thermostatic switch meansresponsive to the temperature of said platen to control the supply ofelectric energy to said heating means to avoid increase in temperatureof said platen above approximately a set value, comprising switch meansconnected in circuit with said heating means and mounted on saidstructural means at a substantial distance above said platen to avoidimmersion of said swtich means in the material upon sinking of saidheater upon melting or softening of the material.

2. An electric heater comprising a platen adapted to be imposed on abody of material, a

4 pair of electric heating elements carried by said platen constructedand arranged to heat said platen to cause said platen to impart heat tosaid material to melt or soften said material, a superstructure disposedabove said platen and comprising a pair of ducts rising from said platenand to which said platen is connected, electric conductors for supplyingelectric energy to said heating elements extending through said duetswith the two conductors for each of said heating elements extending onethrough one of said ducts and the other through the other of said ductsand the two conductors in each of said ducts connected one to one sideof the supply and the other to the other side thereby to reduce or avoidinduction of current in said ducts when the heater is operated onalternating current, and thermostatic switch means responsive to thetemperature of said platen .-to control the supply of electric energy tosaid heating means to avoid increase in temperature of said platen aboveapproximately a set value.

JOHN V. CALHOUN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,070,966 Kicklighter Aug. 19,1913 1,226,350 Mark et al. May 15, 1917 1,756,444 Brockdorfi Apr. 29,1930 2,148,407 Pierson Feb. 21, 1939 2,162,287 Smith June 13, 19392,176,656 Caputo Oct. 17, 1939 2,366,318 Vecchio Jan. 2, 1945

